Browse Prior Art Database

Utilization of System Memory for Fonts

IP.com Disclosure Number: IPCOM000107886D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Cook, JA: AUTHOR [+4]

Abstract

Disclosed is the paradigm of utilizing system memory as the storage place for fonts used by a graphics adapter. As characters are requested by the application, the adapter reads system memory through first party direct memory access (DMA). As new fonts are requested, a protocol with the graphics adapter device driver is used to make the font available to the graphics adapter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

Utilization of System Memory for Fonts

      Disclosed is the paradigm of utilizing system memory as the
storage place for fonts used by a graphics adapter.  As characters
are requested by the application, the adapter reads system memory
through first party direct memory access (DMA).  As new fonts are
requested, a protocol with the graphics adapter device driver is used
to make the font available to the graphics adapter.

      A common font format must be shared by the system software and
the graphics adapter.  The following commands are used by the system
software to control font access: Set Active Font, Remove Active Font,
Font Pinned/Unpinned, Font Must Be Unpinned, and Font Request
Received.  The adapter can issue the following request to the
graphics adapter device driver: Font Request.  A Font Request Block
is used to communicate to the graphics adapter device driver which
font must be pinned or unpinned when a Font Request is issued.

      The font loading sequence is as follows:
      1.  The Set Active Font command is issued to the adapter.
      2.  A character request is issued to the adapter.
      3.  The adapter checks the character cache for the character.
      4.  If not available, the adapter checks if the font is pinned.
      5.  If not, a Font Request Block is built with the needed font
id.
      6.  A Font Request interrupt is issued to the device driver.
      7.  The device driver reads th...